Right on about that cross member. I (a) couldn't figure out where to put a cross-tube given that I have to keep the dash knee bars, and (
figured that that member is hell-for-stout anyway. It's held in by Torx bolts from the door jam side of the dash and my guess is that it accounts for about 30# of the weight difference between a MkII and a MkIII.
We torched a hole through that beast for the downtubes so that, in a side impact, the tubes will run up against the OE structure.
Those last two dash nuts ARE fun, aren't they?
Since the front downtubes run right behind the side vents, I cut the ends off of the lateral tubes in the air ducts that are bonded to the bottom of the dash, and taped them up with aluminum duct tape. (Note here that I don't believe that putting a tube through the dash is permission to take all that stuff out.)
The demister is unaffected and when I turned on the dash vents driving home from getting the cage (AC is great!), it just about blew my eyeballs out, with all of the air coming through the center holes in my face...
It's also interesting that my cage is asymmetrical - the front downtube mounts farther forward on the driver's side floor than on the passenger's, to miss structure on the passenger side while moving foot protection as far forward as possible on the side that counts. We also had to relocate the big wire junction that sits behind the driver's-side vent, shoving it to where that end of the duct used to live.
K